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<html lang="en">
<head>
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  <title>Document</title>
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<body>
  <style>
    .shadow{
      width: 850px;
      height: 600px;
      border: 1px solid #ccc;
      /* 
        box-shadow：水平偏移  垂直偏移  阴影模糊度 阴影尺寸  阴影颜色  inset(内阴影)  
      */
      box-shadow: 1px 1px 5px 1px rgba(0, 0, 0, 0.3) ;
    }
  </style>
  <div class="shadow"></div>
</body>
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